Field of the Invention
The present invention relates to a semiconductor device including a metal wiring having a multilayered structure, and a semiconductor device manufacturing method.
Description of the Related Art
Conventionally, the line & space of a metal wiring having a multilayered structure using aluminum have been downsized by fine-patterning the metal wiring in a semiconductor device to be used in an LSI or the like. As the method of this fine patterning, a hard mask process which performs dry etching on a multilayered film to be a metal wiring by using a hard mask as a mask is known.
As an inconvenience in this hard mask process, however, a pattern defect which occurs when forming the hard mask poses a problem. This pattern defect occurs when forming the hard mask because a deposit or reaction product is formed in a region where the hard mask is not to be formed. Since these deposit and reaction product disturb etching of the multilayered film as a material to be etched, they cause a wiring short of a metal wiring to be formed. These deposit and reaction product which cause this short are probably formed in a hard mask etching step or in a cleaning step after that.
On the other hand, Japanese Patent Application Laid-Open No. 2001-210648 describes an electronic device manufacturing method including, after a hard mask formation step, a step of cleaning an underlying layer whose uppermost portion is formed by a titanium nitride layer and an exposed portion of the hard mask by using a cleaning solution not containing fluorine. According to Japanese Patent Application Laid-Open No. 2001-210648, the formation of a deposit of a reaction product made of titanium in the titanium nitride layer and fluorine can be suppressed by performing cleaning by using the cleaning solution not containing fluorine.
Japanese Patent Application Laid-Open No. 2001-210648 describes that the reaction product of titanium and fluorine can be reduced, but it makes no mention of other reaction products. More specifically, Japanese Patent Application Laid-Open No. 2001-210648 uses a reaction gas containing oxygen in dry etching of the hard mask, but does not refer to the overetching amount after the titanium nitride layer is exposed. Therefore, there is the possibility that a reaction product of titanium and oxygen forms. Even when this reaction product of titanium and oxygen forms, the reaction product may disturb etching of the multilayered film as the metal wiring, and a wiring short may occur.